1. Technical Field
This invention relates to thermomechanical actuators, and more particularly to a system and method which uses pulsed actuation of contoured thermomechanical actuators for enhanced dynamic performance.
2. Background Information
A wide variety of thermomechanical actuators (TMAs) are known in the art. TMAs make use of Joule heating and thermal expansion of materials to generate displacements. Conventional TMAs, which contain slender, constant cross-section microfabricated beams, are well-known for their relatively large force and stroke outputs. Their bandwidths, however, are limited by the heat diffusion process. FIGS. 1A & 1B show common TMA configurations, including constant cross-section beam 30 disposed in parallel beam (FIG. 1A) and chevron (FIG. 1B) configurations. Due to their force/stroke characteristics and ease-of-fabrication, TMAs are frequently found in a variety of meso-/micro-scale devices and positioning systems, such as disclosed in U.S. patent application Ser. No. 11/037,866 (the '866 application), entitled Multiple Degree of Freedom Micro Electro-Mechanical System Positioner and Actuator, filed on Jan. 18, 2005, and which is fully incorporated herein. For instance, they have been used in in-package active fiber alignment devices, micro-scanners used in endoscopes, and meso-/micro-scale nanopositioners. However, drawbacks associated with conventional straight beam TMAs include relatively high power consumption, low efficiency, and low bandwidth, all of which tend to make it difficult to use these TMAs as the basis of practical and efficient devices.
Therefore, there are a number of unresolved issues associated with the use of TMAs, which are addressed by the present invention.